Performance improvement of buck boost converter fed multilevel inverter drive based fuzzy logic controller

Abstract

Voltage Source Inverter (VSI) fed variable speed drives has become an inevitable choice in almost every segment of industrial applications, particularly in medium power ranges. The Multilevel Inverter (MLI) is gaining its popularity due to its merits, which offers better DC-link utilization, lesser harmonic distortion and opportunity to improve the performance through its number of redundant switching states. In particularly, Cascade H-bridge MLI (CHB) is widespread topology due to its simple structure. The MLI connected DC to DC converter is plays a tidy role in variable speed drives and renewable power generation applications. Varity of DC to DC topologies are used in standalone power system (Electrical drives/ utilities application) and grid connected power system applications in the literature. All in all, the two-power conversion (DC to DC and AC to DC) is unavoidable, since the input DC voltage need to be maintained constant which is the important parameter of the DC-link voltage balance of the inverter. The DC to DC converter tied inverters/MLIs needs control system to handle converter and MLI cogitatively. The speed control is normally in open loop. However, these open loop drives are not giving speed -torque performance. Hence, the modern electrical drives are preferred in closed loop controller. The PI controller is the best conventional controller to control a drive speed. Subsequently, the Fuzzy-Logic Controllers (FLCs) and neural network based controller are the better choice compare to PI controller for many applications. The line-current interactions are another important consideration in the VSI fed drive system. Hence, in the close loop drive inner loop behave as a current control loop, whereas the outer one is speed loop. In addition to speed control, the current controls are pre-requisite for providing the smooth